chore: update dependencies and improve package exports

- Updated various dependencies in package-lock.json and package.json, including @nuxtjs/mdc, mermaid, shiki, and others to their latest versions.
- Enhanced package exports in package.json to include types for the default import.
- Added a new export for getMDCParser in src/index.ts.
- Updated optional dependencies for esbuild and rollup packages to their latest versions.